From: Sarika Sharma quic_sarishar@quicinc.com
[ Upstream commit 4541b0c8c3c1b85564971d497224e57cf8076a02 ]
Currently, RX is_mcbc bit is set for packets sent from client as destination address (DA) is multicast/broadcast address, but packets are actually unicast as receiver address (RA) is not multicast address. Hence, packets are not handled properly due to this is_mcbc bit.
Therefore, reset the is_mcbc bit if interface type is AP.
Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1
Signed-off-by: Sarika Sharma quic_sarishar@quicinc.com Reviewed-by: Vasanthakumar Thiagarajan vasanthakumar.thiagarajan@oss.qualcomm.com Link: https://patch.msgid.link/20250411061523.859387-3-quic_sarishar@quicinc.com Signed-off-by: Jeff Johnson jeff.johnson@oss.qualcomm.com Signed-off-by: Sasha Levin sashal@kernel.org ---
**YES** This commit should be backported to stable kernel trees. Here's my extensive analysis: ## Bug Analysis **Root Cause**: The commit fixes a critical packet handling issue where multicast/broadcast packets from clients to an AP are incorrectly marked as multicast (is_mcbc=true) based on the destination address (DA) being multicast, even though they are actually unicast packets since the receiver address (RA) is not multicast. **Impact**: This causes legitimate unicast packets to be mishandled, potentially leading to: - Incorrect encryption handling (using group keys instead of unicast keys) - Packet drops or processing errors - Connectivity issues for clients connected to AP ## Code Changes Analysis The fix involves three key changes: 1. **New peer field (`peer.h:65`)**: Adds `bool ucast_ra_only` field to track when a peer should only receive unicast packets 2. **Peer initialization (`peer.c:386-387`)**: Sets `peer->ucast_ra_only = true` for AP interface types, indicating that packets to/from AP clients should be treated as unicast 3. **Runtime correction (`dp_rx.c:2328-2331`)**: Adds logic to reset the is_mcbc bit when a peer has `ucast_ra_only=true`: ```c /bin /bin.usr-is-merged /boot /dev /etc /home /init /lib /lib.usr-is-merged /lib64 /lost+found /media /mnt /opt /proc /root /run /sbin /sbin.usr-is- merged /snap /srv /sys /tmp /usr /var resetting mcbc bit because mcbc packets are unicast capability_test capability_test.c f2fs_folio_analysis.md ipv4_multipath_analysis.md ipv6_route_allocation_rcu_analysis.md ixgbe_e610_set_phys_id_analysis.md linux lpfc_timeout_analysis.md mac80211_mlo_mbssid_analysis.md pfcp_driver_historical_analysis.md rtl_bb_delay_analysis.md rtw89_mlo_analysis.md tcp_multipath_load_balance_analysis.md test_unaligned_diff test_unaligned_diff.c type_size_check type_size_check.c veth_driver_analysis.md wifi_mlo_mbssid_tx_link_id_analysis.md packets only for AP as STA sends unicast packets. linux/ rxcb->is_mcbc = rxcb->is_mcbc && !peer->ucast_ra_only; ``` ## Backport Suitability Assessment **✅ Fixes Important Bug**: This addresses a real packet handling issue that affects AP functionality and client connectivity. **✅ Small and Contained**: The fix is minimal - adds one field and a simple boolean logic correction. Total change is ~10 lines. **✅ Low Regression Risk**: - Only affects AP mode (`NL80211_IFTYPE_AP`) - Uses conservative approach (resets mcbc bit only when appropriate) - No architectural changes **✅ Clear Side Effects**: The change is isolated to multicast/broadcast packet classification logic and doesn't touch other subsystems. **✅ Subsystem Confined**: Changes are entirely within the ath12k Wi-Fi driver's receive path. ## Comparison with Similar Commits This commit closely matches **Similar Commit #1** and **Similar Commit #3** (both marked YES for backporting): - Fixes multicast/broadcast packet handling issues in ath12k - Small, targeted fixes with clear bug descriptions - Hardware-specific corrections for packet classification - Similar code patterns and impact scope The commit follows the same pattern as other successful ath12k multicast fixes that were deemed suitable for stable backporting. ## Conclusion This is a classic stable tree candidate: it fixes a real user-impacting bug with a minimal, low- risk change that's confined to a single driver subsystem. The fix addresses incorrect packet classification that could cause connectivity issues in AP mode.
drivers/net/wireless/ath/ath12k/dp_rx.c | 5 +++++ drivers/net/wireless/ath/ath12k/peer.c | 5 ++++- drivers/net/wireless/ath/ath12k/peer.h | 3 ++- 3 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/ath/ath12k/dp_rx.c b/drivers/net/wireless/ath/ath12k/dp_rx.c index ff6a709b5042c..cfa96c6216177 100644 --- a/drivers/net/wireless/ath/ath12k/dp_rx.c +++ b/drivers/net/wireless/ath/ath12k/dp_rx.c @@ -2277,6 +2277,11 @@ static void ath12k_dp_rx_h_mpdu(struct ath12k *ar, spin_lock_bh(&ar->ab->base_lock); peer = ath12k_dp_rx_h_find_peer(ar->ab, msdu); if (peer) { + /* resetting mcbc bit because mcbc packets are unicast + * packets only for AP as STA sends unicast packets. + */ + rxcb->is_mcbc = rxcb->is_mcbc && !peer->ucast_ra_only; + if (rxcb->is_mcbc) enctype = peer->sec_type_grp; else diff --git a/drivers/net/wireless/ath/ath12k/peer.c b/drivers/net/wireless/ath/ath12k/peer.c index 792cca8a3fb1b..ec7236bbccc0f 100644 --- a/drivers/net/wireless/ath/ath12k/peer.c +++ b/drivers/net/wireless/ath/ath12k/peer.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: BSD-3-Clause-Clear /* * Copyright (c) 2018-2021 The Linux Foundation. All rights reserved. - * Copyright (c) 2021-2022, 2024 Qualcomm Innovation Center, Inc. All rights reserved. + * Copyright (c) 2021-2022, 2024-2025 Qualcomm Innovation Center, Inc. All rights reserved. */
#include "core.h" @@ -383,6 +383,9 @@ int ath12k_peer_create(struct ath12k *ar, struct ath12k_link_vif *arvif, arvif->ast_idx = peer->hw_peer_id; }
+ if (vif->type == NL80211_IFTYPE_AP) + peer->ucast_ra_only = true; + if (sta) { ahsta = ath12k_sta_to_ahsta(sta); arsta = wiphy_dereference(ath12k_ar_to_hw(ar)->wiphy, diff --git a/drivers/net/wireless/ath/ath12k/peer.h b/drivers/net/wireless/ath/ath12k/peer.h index 5870ee11a8c7e..f3a5e054d2b55 100644 --- a/drivers/net/wireless/ath/ath12k/peer.h +++ b/drivers/net/wireless/ath/ath12k/peer.h @@ -1,7 +1,7 @@ /* SPDX-License-Identifier: BSD-3-Clause-Clear */ /* * Copyright (c) 2018-2021 The Linux Foundation. All rights reserved. - * Copyright (c) 2021-2024 Qualcomm Innovation Center, Inc. All rights reserved. + * Copyright (c) 2021-2025 Qualcomm Innovation Center, Inc. All rights reserved. */
#ifndef ATH12K_PEER_H @@ -62,6 +62,7 @@ struct ath12k_peer {
/* for reference to ath12k_link_sta */ u8 link_id; + bool ucast_ra_only; };
struct ath12k_ml_peer {